Controlled ingrowth feature for antimigration

ABSTRACT

A tubular prosthesis that includes a scaffolding formed by at least one scaffolding filament; a cover; and at least one controlled ingrowth feature constructed and arranged to abut an inner surface of a lumen wall when the prosthesis is implanted in the body lumen. The controlled ingrowth feature may extend inwards or outwards from the prosthesis outer surface. The controlled ingrowth feature may be formed by a scaffolding filament; by a separate filament; by the cover; and combinations thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to U.S.Provisional Application Ser. No. 62/058,821, filed Oct. 2, 2014, theentirety of which is incorporated herein by reference.

BACKGROUND

Stents may be implanted in a variety of body lumens or vessels such aswithin the vascular system, urinary tracts, gastrointestinal tracts,fallopian tubes, coronary vessels, secondary vessels, airways,structural heart (valve frame), etc. They may be self-expanding,expanded by an internal radial force, such as when mounted on a balloon,or a combination of self-expanding and balloon expandable (hybridexpandable). Some stents are partially or fully covered. Migration ofthe stent from its initial site of implantation can be undesirable.

Without limiting the scope of the invention a brief summary of some ofthe claimed embodiments of the disclosure is set forth below. Additionaldetails of the summarized embodiments of the disclosure and/oradditional embodiments of the disclosure may be found in the DetailedDescription of the Invention below.

BRIEF SUMMARY

A prosthesis for controlled tissue ingrowth may comprise a scaffoldingextending from a first prosthesis end to a second prosthesis end; acover; and a controlled tissue ingrowth feature constructed and arrangedto abut an inner surface of a lumen wall when the prosthesis isimplanted in the body lumen, the controlled ingrowth feature selectedfrom the group consisting of protruding elements and dimples; whereinthe controlled ingrowth feature is formed by a scaffolding filament; bya separate filament; by the cover; and combinations thereof.

The prosthesis may be a fully covered prosthesis. The prosthesis has afirst prosthesis end and a second prosthesis end. The prosthesis mayhave a longitudinal length measured from the first prosthesis end to thesecond prosthesis end of about 40 mm to about 400 mm, preferably about60 mm to about 200 mm.

The scaffolding may be selected from the group consisting of: a mesh; aplurality of spaced apart rings; laser cut from a tube; and laser cutfrom a sheet of material formed into a tube. The scaffolding may be asingle layer. The scaffolding may extend from a first prosthesis end toa second prosthesis end. The scaffolding has a scaffolding outersurface. The scaffolding may have a longitudinal length of about 40 mmto about 400 mm, preferably about 60 mm to about 200 mm. The scaffoldingdefines a plurality of scaffolding openings.

The scaffolding openings may have a size of about 1×1 mm to about 5×5mm.

The scaffolding may be formed by a scaffolding filament. The scaffoldingfilament may have a diameter of 0.06 mm to 0.60 mm. The scaffoldingfilament may be bioabsorbable. The scaffolding filament may comprisenitinol, polyethylene terephthalate (PET), or a bioabsorbable material.

The scaffolding may be a mesh. The mesh may be an interwoven mesh. Thescaffolding filament may be interwoven at a uniform angle to form themesh. The interwoven mesh has a plurality of scaffolding filamentcrossings.

The cover may be non-porous. The cover may be attached to thescaffolding outer surface. The cover may have a length equal to thelongitudinal length of the scaffolding. The cover may form theprosthesis outer surface. The cover may have a thickness of about 10 μmto about 400 μm, preferably about 50 μm to about 200 μm, more preferably100 μm to about 150 μm, most preferably about 10 μm. The cover may havea variable thickness or a uniform thickness.

The controlled ingrowth feature may form a maximum of about 30% of anouter surface area of the prosthesis. The controlled ingrowth featuremay be positioned about 5 mm to about 25 mm from the closest prosthesisend; preferably about 10 mm to about 20 mm from the closest prosthesisend; more preferably about 12 mm to about 15 mm from the closestprosthesis end; and most preferably about 15 mm from the closestprosthesis end. The controlled ingrowth feature may be constructed andarranged to abut an inner surface of the lumen wall when the prosthesisis implanted in a body lumen. The controlled ingrowth feature may beconstructed and arranged not penetrate the lumen wall when theprosthesis is implanted in a body lumen.

The controlled ingrowth feature may be a protruding element. Theprotruding element may be selected from the group consisting of aprotruding scaffolding filament section; a separate filament attached tothe scaffolding; a protruding mesh region; and a protruding ring turn.The protruding element is positioned above the scaffolding. Theprotruding element may define a gap with a gap height of about 0.25 mmto about 4.0 mm, preferably about 0.25 to about 2 mm. The gap may be anopen gap or a closed gap. The prosthesis may have only open gaps; onlyclosed gaps; or a combination of open gaps and closed gaps.

The protruding element may be a plurality of protruding elements.

The protruding scaffolding filament section may form about 2.5% to about20% of the outer surface area of the prosthesis. The protrudingscaffolding filament section may extend between two scaffolding filamentcrossings immediately adjacent one another, or may extend over ascaffolding filament crossing. The protruding scaffolding filamentsection has a first end and a second end. The first and second ends ofthe protruding scaffolding filament section may be separated by adistance of 1.5 mm to 7.5 mm. The protruding scaffolding filamentsection may have a rounded shape, a square shape, or a triangular shape.The protruding scaffolding filament section may have no sharp bends. Theprotruding scaffolding filament section may have a rounded shape. Theprotruding scaffolding filament section may be oriented at anon-parallel angle to a longitudinal axis of the prosthesis.

The separate filament may form about 2.5% to about 20% of the outersurface area of the prosthesis. The separate filament may extend betweentwo scaffolding filament crossings immediately adjacent one another, ormay extend over a scaffolding filament crossing. The separate filamenthas a first end and a second end. The first and second ends of theseparate filament may be separated by a distance of 1.5 mm to 7.5 mm.The separate filament may have a rounded shape, a square shape, or atriangular shape. The separate filament may have no sharp bends. Theseparate filament may have a rounded shape. The separate filament may beoriented at a non-parallel angle to a longitudinal axis of theprosthesis.

The protruding mesh region may define an open gap with a maximum gapheight of 0.50 mm to 2 mm. The protruding mesh region has a first edgeand a second edge. The first and second edges may be separated by alongitudinal distance of 2 mm to 10 mm. The protruding mesh region mayform about 2.5% to about 20% of the outer surface area of theprosthesis.

The ring may be formed by a scaffolding filament. Each ring hasinterconnected ring turns. The ring turns include first ring turnsforming the first ring end and second ring turns forming the second ringend. The rings may include a first ring with a variable diameter and asecond ring with a uniform diameter. The first ring has a first ring endwith a first diameter and a second ring end with a second diametergreater than the first diameter, wherein the second ring end is theprotruding element. The second ring end may be positioned above thecover and define a gap therebetween. About 25-75% of the longitudinallength of the first ring, as measured from the first and second ringends, may be positioned above the outer surface of the cover. The gapmay have a maximum gap height of 0.25 mm to 4 mm.

The first ring may either have a truncated cone shape with a singleuniform slope or angle β; or a cylindrical section with a uniformdiameter and a truncated cone section with a single uniform slope orangle β extending from the cylindrical section.

The prosthesis may include a second ring with a first end having a firstdiameter and a second end having the first diameter. The prosthesis mayhave only first rings. The prosthesis may have first and second rings.The rings may be interconnected only by the cover.

The controlled ingrowth feature may be a dimple. The prosthesis may havea single dimple or a plurality of dimples. The dimple may be selectedfrom the group consisting of a dimple cover section of the cover; areinforced dimple comprising a dimple cover section and a section of thescaffolding; a dimple patch; and combinations thereof.

The prosthesis with a dimple may have a single layer of scaffolding, ortwo layers of scaffolding with only one of the two layers of scaffoldingextending from the first prosthesis end to the second prosthesis end.The second layer of scaffolding is a scaffolding patch.

The dimple may span a single scaffolding opening or a plurality ofscaffolding openings. The dimple may span a scaffolding opening having alarger size than the other scaffolding openings. The dimple may define adimple gap with a maximum gap height of about 3 mm. The dimple may havea maximum longitudinal extent of 1 mm to 10 mm. The maximum longitudinalextent of the dimple may be less than the longitudinal length of theprosthesis. The dimple may have a maximum circumferential extent of 1 mmto 10 mm. The maximum circumferential extent may be equal to or lessthan the circumference of the prosthesis.

The cover may comprise a non-dimple cover section and a dimple coversection. The dimple cover section may be entirely surrounded by thenon-dimple cover section. The dimple cover section may form a dimplegap. The dimple gap may have a gap height of about 0.25 mm to about 2.0mm. The dimple may define a single dimple gap or a plurality of dimplegaps.

The dimple is sized so as not to exert a suction force on the lumen wallwhen the prosthesis is implanted. The dimple may have a longitudinalextent of about 1 mm to about 10 mm; a circumferential extent of about 1mm to about 10 mm; an area of about 1 mm² to 100 mm², preferably 5 mm²to about 50 mm², and most preferably 25 mm²; and combinations thereof.The dimple may form about 1% to about 30% of the outer surface area ofthe prosthesis, preferably 5% to 20% of the outer surface area of theprosthesis, and most preferably 10% of the outer surface area of theprosthesis.

Scaffolding may extend over the dimple gap. The scaffolding extendingover the dimple gap may be either a portion of the scaffolding or ascaffolding patch attached to the prosthesis outer surface. A portion ofthe mesh scaffolding may extend over the dimple gap.

A scaffolding patch may extend over the dimple gap and be secured to thenon-dimple cover section.

The dimple gap may span a scaffolding opening having a larger size thanother scaffolding openings.

These and other aspects of a prosthesis of the present disclosure arepointed out with particularity in the detailed description and theclaims annexed hereto and forming a part hereof. However, for furtherunderstanding of the invention reference can be made to the drawingswhich form a further part hereof and the accompanying descriptivematter, in which there is illustrated and described embodiments of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of the invention is hereafter described withspecific reference being made to the drawings.

FIG. 1 is a flat view of an exemplary interwoven prosthesis.

FIG. 2 is a view of a portion of an exemplary prosthesis with a raisedfilament section.

FIG. 3 is a perspective view a raised filament section with a closedgap.

FIGS. 4-5 are cross-sectional views of the raised filament section ofFIG. 3 at line A-A showing no controlled tissue ingrowth.

FIG. 6 is a perspective view of a raised filament section with an opengap.

FIG. 7 is a cross-section view of the raised filament section of FIG. 6at line A-A showing controlled tissue ingrowth.

FIGS. 8A-C show exemplary shapes for a protruding element formed by ascaffolding filament or a separate filament.

FIG. 9 is a view of a portion of an exemplary prosthesis with protrudingmesh regions.

FIG. 10 is a view of an exemplary prosthesis with protruding ring turns.

FIG. 11 is a view of another exemplary prosthesis with protruding ringturns.

FIG. 12 is a view of an exemplary pre-formed ring.

FIGS. 13A-B show schematic views of a protruding ring turn.

FIG. 14 is a schematic view of a tapered mandrel section for forming aring.

FIGS. 15A-C are schematic views of exemplary prostheses with dimples

FIGS. 16A-20 are schematic partial cross-sectional views of a dimple.

FIGS. 21A-C are views of an exemplary method of forming a dimple.

FIG. 22 is a schematic cross-sectional view of an exemplary coatingmandrel.

FIG. 23 is view of an exemplary device for forming dimples in a cover.

FIGS. 24A-C are exemplary configurations of a controlled ingrowthfeature.

DETAILED DESCRIPTION

While this disclosure may be embodied in many different forms, there aredescribed in detail herein specific embodiments of the disclosure. Thisdescription is an exemplification of the principles of the disclosureand is not intended to limit the disclosure to the particularembodiments illustrated.

For the purposes of this disclosure, like reference numerals in thefigures shall refer to like features unless otherwise indicated.

As used in this disclosure, the terms “connect” or “engage” do notinclude “indirect” connection or engagement.

As used in this disclosure, “thickness” is measured radially from theprosthesis outer surface 16 to the prosthesis inner surface 17; “width”is measured in a circumferential direction; and “length is measured in alongitudinal direction.

As used in this disclosure, an “end” is the last part or extremity of anelement, while an “end region” is a region adjacent to, and includes,the “end.”

Prosthesis

A tubular prosthesis or stent 10 as described herein provides forcontrolled tissue ingrowth (see e.g. FIGS. 1-13B and 15A-21C). Thus, theprosthesis 10 may be described as a “controlled tissue ingrowthprosthesis”. “Controlled tissue ingrowth” as used herein means that theprosthesis is constructed and arranged for a pre-determined amount oftissue ingrowth when the prosthesis 10 is implanted.

The prosthesis 10 includes a first prosthesis end 12; a secondprosthesis end 14; a prosthesis outer surface 16; a prosthesis innersurface 17 opposite the prosthesis outer surface 16, the prosthesisinner surface 17 defining the prosthesis lumen; a scaffolding 18; acover 60 and a controlled ingrowth feature 40. The pre-determined amountof tissue ingrowth depends in part on the cover 60 and in part on thecontrolled ingrowth feature 40.

The prosthesis outer surface 16 may be defined by the cover 60 and thecontrolled ingrowth feature 40 (see e.g. FIG. 9), or entirely by thecover 60 (see e.g. FIGS. 2 and 16B). The prosthesis outer surface 16 hasan outer surface area. The prosthesis inner surface 17 may be defined bythe cover 60 and by the scaffolding 18 (see e.g. FIGS. 2, 9, and 16B).The prosthesis inner surface 17 has an inner surface area.

The prosthesis 10 is expandable from a compressed delivery diameter toan expanded implanted diameter. As is known in the art the prosthesis 10may self-expand from the compressed delivery diameter to the expandedimplanted diameter, or may be expanded by a balloon from the compresseddelivery diameter to the expanded implanted diameter. For thisdisclosure, a “diameter” of the prosthesis 10 does not take into accountthe overall height of the controlled ingrowth feature 40. In other wordsthe diameter of the prosthesis is based on the diameter measured fromthe outer surface of the cover 60. As used in this disclosure,“diameter” is the distance of a straight line extending between twopoints and does not indicate a particular cross-sectional shape.

A prosthesis 10 as described herein may have a substantially constantdiameter (see e.g. FIGS. 9 and 15A-18); prosthesis end regions with agreater diameter than the prosthesis middle region (see e.g. FIGS. 2 and10); or a variable diameter (see e.g. FIGS. 11 and 19). The prosthesis10 may have a minimum diameter of about 15 mm and a maximum diameter ofabout 40 mm. The prosthesis end regions may have a diameter of about 15mm to about 35 mm, while the prosthesis middle region may have adiameter of about 15 mm to about 25 mm.

The prosthesis 10 may have a longitudinal length measured from the firstprosthesis end 12 to the second prosthesis end 14 of about 40 mm toabout 400 mm, preferably about 60 mm to about 200 mm.

The prosthesis 10 can be implanted in any suitable body lumen includingthe gastrointestinal system (e.g. colon, esophagus), the hepatobiliarysystem (e.g. biliary tract), the respiratory system (e.g. trachea), thecardiovascular system, and elsewhere in the body.

A. Scaffolding

The prosthesis 10 has a tubular scaffolding 18 that extends from thefirst prosthesis end 12 to the second prosthesis end 14. The scaffolding18 has a scaffolding outer surface, a scaffolding inner surface, and athickness measured from the scaffolding outer surface to the scaffoldinginner surface. The scaffolding 18 may have a longitudinal length ofabout 40 mm to about 400 mm, preferably about 60 mm to about 200 mm; athickness of about 0.06 mm to about 0.60 mm; and combinations thereof.The scaffolding 18 defines a plurality of scaffolding openings 24 (seee.g. FIGS. 1-2, 9, and 15A-22). The scaffolding openings 24 may have asize of about 1×1 mm to about 5×5 mm.

The scaffolding 18 may be in the form of a mesh 22 (see e.g. FIGS. 1-2,9, and 14-20C); a plurality of longitudinally spaced apart rings 28 (seee.g. FIGS. 10-11); laser cut from a tube; or laser cut from a sheet ofmaterial that is welded to form a tube. The prosthesis 10 may have asingle layer of scaffolding 18 (e.g. FIGS. 2-13B, 15A-19, and 21A-22),or two layers of scaffolding 18 (e.g. FIG. 20). As discussed below ingreater detail, where the prosthesis 10 has two layers of scaffolding,only one layer of scaffolding 18 extends from the first prosthesis end12 to the second prosthesis end 14.

The scaffolding 18 is expandable from a compressed delivery diameter toan expanded implanted diameter. Suitable materials for the scaffolding18 are provided below. The structures forming the scaffolding 18 mayhave any suitable cross-sectional shape, for example but not limited toa round cross-sectional shape (see e.g. FIG. 3), or a rectangularcross-sectional shape (not shown). A scaffolding structure, e.g. ascaffolding filament 20, may have a diameter of about 0.06 mm to about0.60 mm. The scaffolding filament 20 can to be a monofilament or amultifilament.

A “mesh” 22 as used in the present disclosure has at least onescaffolding filament 20; a plurality of scaffolding filament crossings26; defines a plurality of scaffolding openings 24; and may be formed byany suitable method, including but not limited to braiding, weaving, andknitting. A prosthesis 10 with a mesh scaffolding may be described as aninterwoven prosthesis. A scaffolding filament 20 forming the meshscaffolding 22 may have a length equal to or greater than thelongitudinal length of the mesh scaffolding 22.

A “ring” 28 as used in the present disclosure extends around the entirecircumference of the prosthesis 10; and has a plurality ofinterconnected ring turns 30, with some ring turns 30 facing the firstprosthesis end 12, and other ring turns 30 facing the second prosthesisend 14 (see e.g. FIGS. 10-11). A ring 28 may be formed by a scaffoldingfilament 20. Thus the scaffolding filament 20 has sections forming thering turns 30 and sections 32 interconnecting the ring turns 30.Sections 32 extending between, and connecting, two ring turns 30 may bestraight or include at least one bend. The scaffolding filaments 20forming the rings 28 of a prosthesis 10 may have the same diameter ordifferent diameters. The ring 28 has a longitudinal length measured fromthe first and second ring ends of about 1 mm to about 30 mm, preferablyabout 5 mm to about 15 mm, most preferably about 10 mm. A prosthesis 10may have rings 28 with different longitudinal lengths or rings 28 withthe same longitudinal length.

A prosthesis 10 formed of rings 28 has at least two rings 28 connectedto one another only by the cover 60 (see e.g. FIGS. 10-11).

A prosthesis 10 may have rings 28 formed of the same material or rings28 formed of different materials.

A prosthesis 10 may have rings 28 with the same radial strength or rings28 of different radial strengths.

A prosthesis 10 may have rings 28 with the same diameter (see e.g. therings forming middle section of the prosthesis 10 shown in FIG. 10), orrings with different diameters (see e.g. FIGS. 10-11).

The rings 28 of a prosthesis 10 may be separated by a substantiallyconstant longitudinal distance 34 (see e.g. FIG. 10) or by differentlongitudinal distances 34 (see e.g. 34 a and 34 b of FIG. 11). Thelongitudinal distance 34 between adjacent rings 28 may be in about 0 mmto about 50 mm. Where the longitudinal distance is about 0 mm, the ringsare in phase and the proximal turns of one ring and the distal turns ofthe adjacent ring are aligned on a line perpendicular to thelongitudinal axis of the prosthesis.

As is known in the art, scaffolding that is formed by laser cutting atube or a sheet of material typically has a plurality of interconnectedstruts that defines a plurality of scaffolding openings. Theinterconnected struts may be arranged in any pattern.

B. Cover

As discussed above, the pre-determined amount of tissue ingrowth dependsin part on the cover 60. The cover 60 is constructed and arranged toprevent tissue from growing through the scaffolding openings 24 and intothe lumen of the prosthesis 10. Examples of suitable materials for thecover 60 are provided below.

To prevent tissue from growing into the lumen of the prosthesis 10, theprosthesis 10 is a fully covered prosthesis. As used in this disclosure,a “fully covered prosthesis” has a cover 60 that extends over thescaffolding outer surface at least from the first prosthesis end 12 tothe second prosthesis end 14 and occludes the scaffolding openings 24.Therefore, the cover 60 has a length equal to, or greater than, thelongitudinal length of the prosthesis 10. About 80% of the cover 60 maybe supported by and/or secured to the scaffolding 18. The prosthesis 10may further include a cover extending over the inner surface of thescaffolding 18. The cover 60 may be non-porous. Alternatively, the cover60 may be porous. For example if the cover 60 is porous, the pore sizeand/or pores location may be constructed and arranged so that there isno tissue growth through the cover 60 and into the lumen of theprosthesis 10; the inner surface of the cover 60 may have a impermeablelayer the prevents tissue growth therethrough; and combinations thereof.

The cover 60 may have a thickness of about 10 μm to about 400 μm,preferably about 50 μm to about 200 μm, more preferably 100 μm to about150 μm, most preferably about 100 μm. The cover 60 may have a variablethickness (see e.g. FIG. 22) or a uniform thickness (see e.g. FIG. 17).Although the cover 60 typically has a thickness less than the diameterof the scaffolding filament 20, the cover 60 may have a thickness equalto or greater than the diameter of the scaffolding filament 20. Wherethe cover 60 has a thickness greater than the diameter of thescaffolding filament 20 the cover 60 extends over the outer surface ofthe scaffolding 18. Where the cover has a thickness less than thediameter of the scaffolding filament 20, the scaffolding filament 20 mayprotrude slightly outward from outer surface of the cover 60. The heightof the slight outward protrusion of the scaffolding filament 20 isminimal (e.g. a height of about 0.5 mm). Thus, the prosthesis outersurface 16 is substantially uniform.

C. Controlled Ingrowth Feature

As discussed above, the pre-determined amount of tissue ingrowth whenthe prosthesis 10 is implanted depends in part on the controlledingrowth feature 40. Some features of the controlled ingrowth featurethat affect the pre-determined amount of tissue ingrowth include theamount of the prosthesis outer surface 16 that is formed by thecontrolled ingrowth feature 40; the gap height h and overall height ofthe controlled ingrowth feature; and combinations thereof.

As discussed below in greater detail, the controlled ingrowth feature 40may form a maximum of about 30% of the prosthesis outer surface 16.

Each controlled ingrowth feature 40 defines a gap 56 between thecontrolled ingrowth feature 40 and the prosthesis outer surface 16. Thegap 56 has a maximum extent or height h measured from the prosthesisouter surface 16 (hereinafter “gap height h”; see e.g. FIGS. 2, 4, 8A-C,9, 13A, and 16B-19). Depending on the type of controlled ingrowthfeature 40, the controlled ingrowth feature 40 may have maximum gapheight h of about 0.25 mm to about 4 mm, or about 0.5 mm to about 2 mm.

The controlled ingrowth feature 40 is positioned between the first andsecond prosthesis ends 12, 14, and may be parallel, or non-parallel, tothe longitudinal axis of the prosthesis 10. Exemplary configurations ofthe placement of the controlled ingrowth feature(s) 40 along thelongitudinal length of the prosthesis 10 are shown in FIGS. 2, 9-11, 14,and 22A-E. A longitudinal distance separates the controlled ingrowthfeature 40 from each prosthesis end 12, 14. In other words, a section ofthe prosthesis 10 separates the controlled ingrowth feature 40 and theclosest prosthesis end 12, 14. The controlled ingrowth feature may bepositioned about 5 mm to about 25 mm from the closest prosthesis end12,14; preferably about 10 mm to about 20 mm from the closest prosthesisend 12,14; more preferably about 12 mm to about 15 mm from the closestprosthesis end 12,14; and most preferably about 15 mm from the closestprosthesis end 12,14. For example, as shown in FIG. 2, the closestprosthesis end to the controlled ingrowth feature 40 is a distancebeyond the top edge of the figure and the end of the controlled ingrowthfeature 40 closest to the top edge of the figure is a distance from thatclosest prosthesis end. Without being bound by theory, having alongitudinal distance separating an end or edge of a controlled ingrowthfeature 40 from the closest prosthesis end 12, 14 mitigates granulationtissue formation at or near the prosthesis end 12, 14 when theprosthesis 10 is implanted in a body lumen.

Forming the controlled ingrowth feature 40 is part of the method offorming the prosthesis 10 so that, once formation of the prosthesis 10is completed, the prosthesis 10 has a controlled ingrowth feature 40. Inother words, the prosthesis has a controlled ingrowth feature 40 at alltimes and the presence of the controlled ingrowth feature is notdependent on the prosthesis being in a particular state, e.g. acompressed delivery state or an expanded deployed state.

A controlled ingrowth feature 40 may extend outwardly from theprosthesis outer surface 16 of the prosthesis 10 (see e.g. FIGS. 2-11),or may extend inwardly from the prosthesis outer surface 16 (see e.g.FIGS. 14-19). The controlled ingrowth feature 40 may be formed by ascaffolding filament 20; by a separate filament 48; by the cover 60, andcombinations thereof.

C.1. Outwardly Extending Controlled Ingrowth Feature/Protruding Element

As discussed above, the controlled ingrowth feature 40 may extendoutwardly. A controlled ingrowth feature 40 that extends outwardly canbe described as an outwardly extending controlled ingrowth feature or asa protruding element (hereinafter “protruding element”). Thus, as usedin this disclosure, a “protruding element” extends outwardly and has afirst end/edge and a second end/edge positioned at the outer surface ofthe cover 60.

A prosthesis 10 with a protruding element 40 has a single layer ofscaffolding 18 (see e.g. FIGS. 2-13B). The protruding element 40 may beformed by a part of the scaffolding 18 (see e.g. FIGS. 2 and 9-11), orby a separate filament 48 incorporated into the scaffolding 18 (see e.g.FIGS. 6). Examples of a part of the scaffolding 18 forming a protrudingelement 40 include: a section of a scaffolding filament 20 forming themesh 22 (see e.g. FIG. 2; referred hereinafter as a protrudingscaffolding filament section 42); a region of the mesh 22 (see e.g. FIG.9; referred hereinafter as a protruding mesh region 44); and a ring turn30 that protrudes (see e.g. FIGS. 10-11; referred hereinafter as aprotruding ring turn 46).

As discussed above, the pre-determined amount of tissue ingrowth dependsin part on the amount of the prosthesis outer surface that is formed bythe protruding element 40. For protruding elements 40 that are a part ofthe scaffolding 18, a separate filament 48 incorporated into thescaffolding, or a protruding scaffolding filament section 42, a maximumof about 20% of the prosthesis outer surface 16 is formed by theprotruding elements 40 (see e.g. FIGS. 2-9). Thus for these embodiments,about 80% of the cover is supported by and/or secured to the scaffolding18. These types of protruding elements 40 may form about 2.5% to about20% of the prosthesis outer surface 16. Without being bound by theory,having a maximum of about 20% of the prosthesis outer surface 16 withprotruding elements 40 may maintain adhesion between the cover 60 andthe scaffolding 18, thereby preventing tissue ingrowth through thescaffolding 18; may prevent the cover 60 from being pulled away from thescaffolding 18 by tissue ingrowth; may prevent collapse of the cover 60into the lumen of the prosthesis; and combinations thereof.

For protruding elements 40 that are protruding ring turns 46, a maximumof about 75% of the prosthesis outer surface 16 is formed by theprotruding elements 40. As discussed below in greater detail, this typeof protruding element 40 may form about 25% to about 75% of theprosthesis outer surface 16.

The pre-determined amount of tissue ingrowth depends in part on the gapheight h of the protruding element 40 and the overall height of theprotruding element 40. The gap height h is measured from the prosthesisouter surface 16 to the protruding element 40. The gap height h does notinclude the diameter of the protruding element 40. The combination ofthe gap height h and the diameter of the protruding element 40 is ameasure of the overall height of the protruding element 40.

The overall height of the protruding element 40 is constructed andarranged so that the protruding element 40 does not puncture or jab intothe lumen wall after the prosthesis 10 to is implanted in a body lumen.In other words, when the prosthesis 10 is implanted the protrudingelement 40 abuts/contacts the lumen wall 80 but does not penetrate thelumen wall 80. The contact of the protruding element 40 against thelumen wall irritates the tissue of the lumen wall 80, which inducestissue growth around the protruding element 40 (see e.g. FIGS. 4-5 and7).

The gap height h and the overall height are substantially fixed becausethe protruding element 40 has limited flex. Because the protrudingelement 40 has limited flex, the gap height h and the overall height ofthe protruding element 40 is substantially uniform. In other words,because the movement of the protruding element 40 up or down relative tothe cover 60 is minimized, the protruding element 40 has a substantiallyuniform gap height h and a substantially uniform overall height. Aprosthesis 10 with protruding elements 40 with a uniform gap height hand overall height has controlled tissue ingrowth. In contrast, aprosthesis with outwardly extending features that flex up or downrelative to a covering would have uncontrolled tissue ingrowth. Forprotruding elements 40 that are a part of the scaffolding 18, a separatefilament 48 incorporated into the scaffolding, or a protrudingscaffolding filament section 42, the gap height h and the overall heightare substantially fixed because the protruding element 40 has a presetcurvature that limits flex of the protruding element 40.

Depending on the configuration of the protruding element 40, the gapheight may be uniform or variable (see e.g. FIGS. 8-11). Where the gapheight h is variable, the gap height h is the maximum gap height h.Depending on the type of protruding element 40, the maximum gap height hmay be about 0.25 mm to about 4 mm, or about 0.50 mm to about 2 mm.

As discussed above, prosthesis outer surface 16 is considered to besubstantially uniform even though the scaffolding filament 20 mayprotrude slightly from the outer surface of the cover 60. Thus, theheight of the outward protrusion from the outer surface of the cover 60is not considered for the purpose of measuring the gap height h and theoverall height of a protruding element 40.

The protruding element 40 may have a diameter of about 0.06 mm to about0.6 mm. Thus, the overall height of the protruding element may be about0.56 mm to about 2.6 mm. The overall height of the protruding element 40may be described with reference to the diameter of the protrudingelement 40. The overall height of the protruding element 40 may be about4× to about 9× the diameter of the protruding element 40. For example,where the protruding element 40 has a diameter of 0.06 mm and an overallheight of 0.56 mm the overall height is about 9.3 times the diameter ofthe protruding element 40. Similarly, where the protruding element 40has a diameter of 0.6 mm and an overall height of 2.6 mm, the overallheight is about 4.33 times the diameter of the protruding element 40.

The gap height h and overall height of the protruding element 40 maydepend on the intended implantation site. For example when theprosthesis 10 is constructed for implantation in the esophagus, theoverall height of the protruding element 40 is between about 0.1 mm andabout 2 mm because the lumen wall in the esophagus varies from 1.5 mm to4 mm, depending on location and state of swallowing. The range for theoverall height allows for tissue growth around the protruding element 40without a risk of eroding completely through the lumen wall of theesophagus. Where the prosthesis 10 is constructed for implantation inanatomy further down the gastrointestinal tract, such as the large andsmall bowel, the protruding element 40 may have a smaller overallheight, between about 0.5 mm and about 1 mm, as the lumen wall isthinner in these regions.

For a protruding element 40, the pre-determined amount of tissueingrowth also depends on whether tissue grows entirely or partiallyaround the protruding element 40 (see e.g. FIGS. 4-5 and 7). Tissuegrows entirely around a protruding element 40 with a gap 56 that is open(an “open gap”), while tissue grows partially around a protrudingelement 40 with a gap 56 that is closed (a “closed gap”). As used inthis disclosure an “open gap” is not enclosed by, or filled with, thematerial forming the cover 60 (see e.g. FIG. 7), while a “closed gap” isenclosed by, or filled with, the material forming the cover 60 (see e.g.FIGS. 4-5). It is noted that the gap height h does not depend on whetherthe gap 56 is to be an open gap or a closed gap.

Although a prosthesis 10 with an open gap 56 may be removed afterimplantation, less trauma to the lumen wall 80 occurs if the prosthesishas closed gaps 56 because the cover material around the protrudingelement 40 provides for a passageway for removal of the protrudingelement 40 from the lumen wall. A prosthesis 10 may have only protrudingelements 40 with open gaps 56; only protruding elements 40 with closedgaps 56; or a combination of protruding elements 40 open gaps 56 andprotruding elements 40 with closed to gaps 56.

A closed gap 56 may be described as being defined by a section the cover60 extending up from the prosthesis outer surface 16, around theprotruding element 40, and down to the prosthesis outer surface 16, oras a film of covering material that goes up and connects to theunderside of the protruding element 40 (see e.g. FIGS. 4-5). Thissection of the cover 60 can be described as a gap section.

Alternatively, a closed gap 56 may be described as being formed by alayer of cover material that extends up from the prosthesis outersurface 16, around the protruding element 40, and down to the prosthesisouter surface 16. This layer of cover material forming the closed gap 56may have a thickness less than the thickness of the cover 60. The covermaterial forming a closed gap 56 may have a thickness less than thediameter of the protruding element 40 (see e.g. FIG. 4); greater thanthe diameter of the protruding element (see e.g. FIG. 5); andcombinations thereof (see e.g. FIG. 5). As used in this disclosure, aclosed gap is an “enclosed closed gap” if there is a space between thematerial forming the cover 60 on either side of the protruding element40, (see e.g. FIG. 4), whereas a closed gap is a “filled closed gap” ifthe cover material on both sides of the protruding element 40 are incontact so that there is no space therebetween (see e.g. FIG. 5).

The protruding element 40 is also constructed so that the protrudingelement 40 does not include any sharp turns or bends. The sharpness of aturn or bend may be described by referring to the curvature of theturn/bend. Curvature is a measure of how quickly a tangent line turns ona curve. A curve with a larger curvature bends more sharply (e.g. insidelane of a track) than another curve with a smaller curvature (e.g.outside lane of a track). Curvature is also the reciprocal of radius.Thus a small curvature implies a large radius. The turn of a protrudingelement 40 may have a radius of curvature of about 0.254 mm to about0.00254 mm (0.010 inches to about 0.0001 inches). The radius ofcurvature is a measure of the radius of a circular arc which bestapproximates the curve at a particular point. An example of a “sharp”turn is a turn greater than 45° (0.785 radians) that has a radius lessthan 0.010 inches (0.254 mm).

C.1.a. Scaffolding Filament/Separate Filament

As discussed above, the protruding element 40 may be a protrudingscaffolding to filament section 42 of a scaffolding filament 20 formingthe mesh 22 (see e.g. FIG. 2), or a separate filament 48 incorporatedinto a mesh scaffolding 18 (see e.g. FIG. 6). In either case theprotruding element 40 is formed by a single filament 20, 48. Someexemplary shapes for the protruding scaffolding filament section 42 andthe separate filament 48 include rounded (see e.g. FIGS. 3 and 6);square shape (see e.g. FIG. 8A); wave shaped (see e.g. FIG. 8B); andtriangular shaped (see e.g. FIG. 8C).

An individual scaffolding filament 20 of the mesh scaffolding 18 mayhave no protruding scaffolding filament section 42; one (1) protrudingscaffolding filament section 42; or a plurality (2+) of protrudingscaffolding filament sections 42. Each protruding scaffolding filamentsection 42 extends from a first end 43 a to a second end 43 b (see e.g.FIGS. 8A-C). In one aspect, each end of a protruding scaffoldingfilament section 42 is located at a scaffolding filament crossing 26(see e.g. FIG. 2). The scaffolding filament crossings 26 may bepositioned immediately adjacent one another (see e.g. the twoscaffolding filament crossings 26 identified at the left end region ofthe prosthesis 10 of FIG. 1); or may be separated by at least onescaffolding filament crossing 26 (see e.g. the two scaffolding filamentcrossings 26 identified at the right end region of the prosthesis 10 ofFIG. 1; in other words, the protruding scaffolding filament section 42extends over, or positioned above, at least one scaffolding filamentcrossing 26).

The two ends 43 a, 43 b of a protruding scaffolding filament section 42are separated by a distance d2 measured along the prosthesis outersurface 16 (see e.g. FIGS. 8A-C). The protruding scaffolding filamentsection 42 is constructed and arranged to that the distance d2 providesthe cover 60 with sufficient support to withstand pressure applied bytissue ingrowth so that the cover 60 is not damaged or broken by tissueingrowth when the prosthesis 10 is implanted. The distance d2 does notinclude the diameter of the scaffolding filament 20 and may be about 1.5mm to about 7.5 mm. Where the ends 43 a, 43 b are located at scaffoldingfilament crossings 26 positioned immediately adjacent one another, thedistance d2 is equal to the length of the cell/opening 24 of the braidedscaffolding 18.

Each protruding scaffolding filament section 42 defines a gap 56 with aheight h of about 0.5 mm to about 2 mm measured from the outer surfaceof the cover 60; a distance d2 from the first end 43 a to the second end43 b of about 1.5 mm to about 7.5 mm; and combinations thereof.

The prosthesis 10 may have at least one separate filament 48 (see e.g.FIG. 6). Each separate filament 48 has a first end region 52 forming afirst filament end, a second end region 54 forming as second filamentend, and a protruding section 50 with a first end 43 a connected to thefirst end region 52 and a second end 43 b connected to the second endregion 54 (see e.g. FIGS. 8A-C).

The separate filament 48 may have any suitable cross-sectional shape,for example but not limited to a round cross-sectional shape or arectangular cross-sectional shape (not shown). The separate filament 48may have a diameter of about 0.06 mm to about 0.6 mm. The separatefilament 48 has a length less than the longitudinal length of thescaffolding 18. The separate filament 48 may have a length less than thelength of the scaffolding filament 20 forming the scaffolding to whichthe separate filament 48 is secured.

The separate filament 48 may be parallel to a scaffolding filament 20(not shown). The end regions 52, 54 of the separate filament 48 aresecured to the scaffolding 18 by any suitable manner. For example theseparate filament 48 can be secured to the scaffolding 18 byinterweaving the end regions 52, 54 into the scaffolding 18; by bondingthe end regions 52, 54 to the scaffolding 18; by welding the end regions52, 54 to the scaffolding 18; and/or by wrapping the end regions 52, 54around a scaffolding filament 20. Thus, the ends of the separatefilament 48 are free ends until the end regions 52, 54 are secured tothe scaffolding 18. Although the separate filament 48 is secured to thescaffolding 18, the separate filament 48 is not a layer of scaffolding18 as used herein. Thus, a prosthesis 10 with a separate filament 48 hasa single layer of scaffolding 18.

Each protruding section 50 defines a gap 56 with a height h of about 0.5mm to about 2 mm measured from the outer surface of the cover 60; adistance d2 from the first end 43 a to the second end 43 b of about 1.5mm to about 7.5 mm measured along the prosthesis outer surface 16, notincluding the diameter of the separate filament 48; has an overallheight of about 0.56 mm to about 2.6 mm; and combinations thereof.

Where a prosthesis has more than one scaffolding filament section orseparate filament, the protruding scaffolding filament sections 42 orprotruding sections 50 may have the same orientation, for example aright hand orientation (see e.g. FIG. 2). Further, the protrudingscaffolding filament sections 42 or protruding sections 50 may besubstantially aligned about the circumference of the prosthesis 10 (seee.g. FIG. 2 where the protruding scaffolding filament sections 42 havesubstantially the same longitudinal position but differentcircumferential positions).

C.1.b. Mesh Regions

As discussed above, the protruding element 40 may be a protruding meshregion 44 (see e.g. FIG. 9). The scaffolding filament(s) 20 forming themesh 22 and the protruding mesh region 44 may be have a uniform braidangle. In other words, the braid angle of the scaffolding filament(s) 20in the protruding mesh region 44 is the same as the braid angle of thescaffolding filament(s) 20 in the rest of the mesh 22. An example of asuitable uniform braid angle is 100°.

The protruding mesh region 44 includes a plurality of scaffoldingfilament crossings 26 positioned above the prosthesis outer surface 16which is defined by the cover 60 (see e.g. FIG. 9). The protruding meshregion 44 has a rounded shape with no sharp bends or turns (see e.g.FIG. 9). Attributes of bends/turns that are not sharp are discussedabove.

The protruding mesh region 44 has a longitudinal extent/distance dmeasured from a first end/edge of the protruding mesh region 44 to asecond end/edge of the protruding mesh region 44. The longitudinaldistance d of the protruding mesh region 44 is sized so that the meshscaffolding provides the cover 60 with sufficient support to withstandpressure applied by tissue ingrowth so that the cover 60 is not damagedor broken by tissue ingrowth when the prosthesis 10 is implanted. Thelongitudinal distance d may be about 2 mm to about 10 mm.

The gap height h of the protruding mesh region 44 is variable. Themaximum gap height h of the protruding mesh region is about 0.5 mm toabout 2 mm. The area of the gap 56 defined by a protruding mesh region44 depends on the diameter of the prosthesis 10, the gap height h, andthe longitudinal distance d of the protruding mesh region 44.

A prosthesis 10 may have one or a plurality of protruding mesh regions44. For a prosthesis 10 with a plurality of protruding mesh regions 44,adjacent protruding mesh regions 44 are separated by a minimumlongitudinal distance of about 20 mm.

C.1.c. Ring Turns

As discussed above, the prosthesis 10 may have a single layer ofscaffolding 18 and a to protruding element 40 (see e.g. FIGS. 10-11).The protruding element 40 may be a protruding ring turn 46 of a ring 28.Where the protruding element 40 is a protruding ring turn 46, the cover60 may have a thickness of about 40 μm to about 400 μm.

A ring 28 with a protruding ring turn 46 may be described as having afirst diameter 27 a at a first ring end and a second, greater, diameter27 b at a second ring end (see e.g. FIG. 12). When a ring 28 with alarger diameter at the second ring end than the first ring end isincorporated into a prosthesis 10, the ring turns 30 at the second ringend are protruding ring turns 46 (see e.g. FIG. 12). Thus, the entiresecond ring end may be described as a protruding element 40.

A ring 28 with a protruding ring turn 46 may have a single, uniformslope or angle β from the first ring end to the second ring end. Thistype of ring 28 can be described as a truncated cone (see e.g. FIG. 12).It is noted that even when a section 32 of the scaffolding filament 20includes a bend, the ring 28 has a single uniform slope or angle βbecause the bend does not affect the distance of the protruding ringturn from the outer surface of the cover 60. Alternatively a ring 28with a protruding ring turn 46 may have a cylindrical section and atruncated cone section, where the cylindrical section forms one end ofthe ring 28 and has a uniform diameter, and the truncated cone sectionforms the other end of the ring 28 and has a single, uniform slope orangle from the cylindrical section to the end of the ring 28. A ring 28with either of these two configurations has protruding ring turns 46that extend outwardly at a single uniform slope or angle β.

As discussed above, the ring 28 has a longitudinal length. About 25-75%of the longitudinal length of the ring 28, as measured from the firstand second ring ends, may be positioned above the outer surface of thecover 60. Thus for a ring 28 in the shape of a truncated cone, aprotruding ring turn 46 may include a portion of each of the twosections 32 connected the protruding ring turn 46 (see e.g. FG. 13A).For a ring 28 with a cylindrical section and a truncated cone section,the truncated cone section is constructed and arranged to be positionedabove the outer surface of the cover 60. Thus, the truncated conesection may have a length of about 25% to about 75% of the longitudinallength of the ring 28.

The protruding ring turn 46 has a gap height h of about 0.25 mm to about4 mm, preferably about 0.25 mm to about 2 mm (see e.g. FIGS. 13A-B). Fora given uniform slope β, the gap height h correlates either to thepercentage of the longitudinal length of the ring 28 to or to thepercentage of the truncated cone section that is positioned above theouter surface of the cover 60. For example, for a given uniform slope β,the greater the percentage of the ring or truncated cone section that ispositioned above the outer surface of the cover, the greater the gapheight h. In other words, the gap height h at 25% is greater than thegap height h at 75%. For a given gap height h, the uniform slope βcorrelates to the percentage of the longitudinal length of the ring 28or the percentage of the truncated cone section that is positioned abovethe outer surface of the cover 60. For example, for a given gap heighth, the greater the percentage of the ring or truncated cone section thatis positioned above the outer surface of the cover, the greater theuniform slope β. In other words, a greater uniform slope β is needed toobtain a given gap height when 75% is positioned above the outer surfaceof the cover than when 25% is positioned above the outer surface of thecover.

A prosthesis 10 has at least one ring 28 with a protruding ring turn 46.A prosthesis 10 may comprise only rings 28 having at least oneprotruding ring turn 46 (see e.g. FIG. 10); or a combination of rings 28a having at least one protruding ring turn 46, and rings 28 b having noprotruding ring turns (see e.g. FIG. 11). The protruding ring turns 46of a prosthesis 10 may be oriented toward the same prosthesis end 12,14, or may be oriented towards both prosthesis ends 12, 14 (see e.g.FIGS. 10-11). An individual ring 28 may have protruding ring turns 46facing toward only one prosthesis end 12, 14, or protruding ring turns46 facing both prosthesis ends 12, 14.

C.2. Inwardly Extending Controlled Ingrowth Feature/Dimple

A controlled ingrowth feature 40 that extends inwardly can be describedas an inwardly extending controlled ingrowth feature or as a dimple(hereinafter referred to as a “dimple”). In other words, a dimple 40 ispositioned a smaller distance from, or is closer to, the longitudinalaxis of the prosthesis than the prosthesis outer surface 16 (see e.g.FIGS. 15A-21C). As used in this disclosure, a “dimple” extends inwardlyfrom a prosthesis outer surface 16 of an implanted prosthesis and has anedge positioned at the prosthesis outer surface 16. For a prosthesis 10comprising a dimple 40, the prosthesis outer surface 16 is defined bythe cover 60.

A dimple 40 may be entirely formed by a portion of the cover 60extending over the outer surface of the scaffolding 18 (see e.g. FIGS.15A-18 and 20); may be formed by a to portion of the cover 60 and aportion of the scaffolding 18 (see e.g. FIG. 19); may be formed by adimple patch 68 (see e.g. FIGS. 21A-C); and combinations thereof.

A dimple 40 has a longitudinal extent (distance d) measured along theprosthesis outer surface 16 of about 1 mm to about 10 mm; acircumferential extent measured along the prosthesis outer surface 16 ofabout 1 mm to about 10 mm; an area of about 1 mm² to 100 mm², preferablyabout 5 mm² to about 50 mm², most preferably 25 mm²; and combinationsthereof. Where the longitudinal or circumferential extent is variable,the longitudinal/circumferential extent refers to the maximum extent.

As discussed above, the pre-determined amount of tissue ingrowth dependsin part on the amount of the prosthesis outer surface 16 that is formedby the dimple(s) 40. The dimple(s) cover a maximum of about 30% of thescaffolding outer surface. The dimple(s) 40 may cover about 1% to about30% of the scaffolding outer surface, preferably about 5% to about 20%of the scaffolding outer surface, and most preferably 10% of thescaffolding outer surface.

When the prosthesis 10 expands to an implanted diameter, the dimple 40defines a gap 56 for tissue ingrowth (see e.g. FIGS. 16B and 17-19). Thegap 56 of a dimple 40 may also be described as a dimple gap or dimplerecess. It is noted that the dimple 40 may or may not extend inward intothe prosthesis lumen at other times (e.g. during delivery). A dimple 40may define one (1) dimple gap 56 (see e.g. FIGS. 17-19); or a pluralityof dimple gaps 56 (see e.g. FIG. 16B). The dimple gap 56 is constructedand arranged so that the dimple 40 does not exert suction on the lumenwall when the prosthesis 10 is implanted. A dimple gap 56 may extendinward through a single scaffolding opening 24 (see e.g. FIG. 16B) orspan several scaffolding openings (see e.g. FIGS. 18 and 20-21C). Thescaffolding opening 24 into which the dimple 40 extends may have a sizeequal to the other scaffolding openings 24 (see e.g. FIG. 16B), orgreater than the other scaffolding openings 24 (see e.g. FIG. 17).

The dimple gap 56 has a maximum gap height h measured from the outersurface of the cover 60 to the bottom of the dimple gap 56 (see e.g.FIGS. 16B-19). The maximum gap height h is about 0.5 mm to about 3 mm,preferably about 1 mm to about 2 mm, and most preferably about 1.5 mm.The overall size of the dimple gap 56 depend at least in part on thesize of the scaffolding openings 24; the gap height h; and combinationsthereof (see e.g. FIGS. 16A-16C and 21A-21C).

A prosthesis 10 with a dimple 40 may have a single layer of scaffolding18 (see e.g. FIGS. 16A-19 and 21A-22) or two layers of scaffolding 18(see e.g. FIG. 20). The prosthesis 10 may have a single (1) dimple 40 ora plurality of dimples 40. The dimple(s) 40 may be arranged in acircumferential ring (see e.g. FIGS. 15A-C and 24C); helically (see e.g.FIG. 24A); an island surrounded by a non-dimple portion of theprosthesis (see e.g. FIGS. 15A-C and 24A-C); and combinations thereof.Where the dimple 40 forms a circumferential ring, the ring may extendaround the entire circumference of the prosthesis 10 or only a portionof the circumference of the prosthesis 10. For each of thesearrangements the dimple 40 covers only a portion of the outer surfacearea of the prosthesis 10 and only a portion of the inner surface areaof the prosthesis 10.

C.2.a. Inwardly Extending Controlled Ingrowth Feature/Dimple EntirelyFormed by Cover

As discussed above, a dimple 40 may be entirely formed by the cover 60(see e.g. FIGS. 15A-18 and 20). Thus the cover 60 has at least onedimple cover section 64 forming a dimple 40. Each dimple cover section64 is entirely surrounded by a non-dimple cover section 66 of the cover60 (see e.g. FIG. 15A). As used herein a “non-dimple cover section” is asection of the cover 60 that has a size equal to the size of thescaffolding covered thereby, and a “dimple cover section” is a sectionof the cover 60 that has a size greater than the size of the scaffoldingcovered thereby.

A cover 60 with a dimple cover section 64 and a non-dimple cover section66 may have a uniform thickness. In other words, the thickness of thedimple cover section 64 is equal to the thickness of the non-dimplecover section 66.

Scaffolding 18 may extend over a gap 56 formed by the dimple 40 (seee.g. FIG. 20). The scaffolding extending over the gap 56 may be aportion of the scaffolding 18 forming the prosthesis (see e.g. FIG. 18),or a scaffolding patch 18 b attached to the prosthesis outer surface 16(see e.g. FIG. 20). Where the scaffolding extending over the gap is aportion of the scaffolding 18, the prosthesis 10 has a single layer ofscaffolding 18.

Where the scaffolding extending over the gap 56 is a scaffolding patch18 b, the prosthesis 10 may be described as having two layers ofscaffolding. However, only one of the two layers of scaffolding extendsfrom the first prosthesis end 12 to the second prosthesis end 14. Theother layer of scaffolding 18, the scaffolding patch 18 b, has a patchlongitudinal extent pd and a patch circumferential extent that issufficiently large to cover the gap 56 but extends over only a portionof the scaffolding 18. In other words, the area of the scaffolding patch18 b is less than the outer surface area of the prosthesis 10. Ascaffolding patch may be attached to the prosthesis outer surface 16 byany suitable means.

C.2.b. Inwardly Extending Controlled Ingrowth Feature/Dimple Formed byCover and Scaffolding

As discussed above, a dimple 40 may be formed by a portion of the cover60 and a portion of the scaffolding 18 (see e.g. FIG. 19). Hereinafter,this type of dimple is referred to as a reinforced dimple 40. Becausethe scaffolding 18 forms a part of the reinforced dimple 40, theprosthesis 10 has a variable diameter.

The scaffolding 18 of a reinforced dimple 40 may be positioned betweenthe outer and inner surface of the reinforced dimple, or may form a partof the inner surface of the reinforced dimple.

C.2.c. Inwardly Extending Controlled Ingrowth Feature/Dimple Patch

As discussed above, a dimple 40 may be formed by a dimple patch 68 (seee.g. FIGS. 21A-C). The dimple patch 68 may cover an area 36 with nocover (see e.g. FIG. 21B). The size of the area 36 may be greater thanthe size of the scaffolding openings 24. The size of the dimple patch 68is greater than the size of the area 36 but less than the size of thecover 60. In other words, the surface area covered by the dimple patch68 is less than outer surface area of the cover 60. The size of thedimple patch 68 is also sufficiently large to form a dimple 40 when theprosthesis is implanted.

The area 36 may include scaffolding 18 (portion of scaffolding with nocover, see e.g. FIGS. 21B-C); or no scaffolding. Any suitable means canbe used to form an area 36 with no scaffolding. For example, a region ofthe scaffolding 18 may be removed leaving an opening with a greater sizethan the scaffolding openings 24; or formation of the area 36 may be apart of forming the scaffolding, e.g. forming the scaffolding includesforming a scaffolding opening 24 that is larger than other scaffoldingopenings 24.

As can be seen in FIGS. 24A-C, the dimple patch 68 is attached to theprosthesis outer surface 16. The dimple patch 68 may be attached to theprosthesis outer surface 16 by any suitable means.

A scaffolding patch may be combined with a dimple patch 68. Thescaffolding patch has a size equal to or less than the size of thedimple patch. The scaffolding patch may be positioned over the dimplepatch 68. This configuration may look similar to that shown in

FIG. 20 except that the wall of the prosthesis will have three layers,an inner layer of scaffolding; a middle layer formed by the dimple patch68 extending over an area 36; and an outer layer formed by thescaffolding patch. This type of dimple patch can be described as areinforced dimple patch. Alternatively, the scaffolding patch may bepositioned between the inner and outer surfaces of the dimple patch.

D. Optional Prosthesis Features

A prosthesis 10 as described above may include one or more areas, bands,coatings, members, etc. that is (are) detectable by imaging modalitiessuch as X-Ray, MRI, ultrasound, etc. In one aspect at least a portion ofthe prosthesis 10 is at least partially radiopaque.

A prosthesis 10 as described above may be configured to include one ormore mechanisms for the delivery of a therapeutic agent. As used in thisdisclosure, a “therapeutic agent” is a drug or other pharmaceuticalproduct used to treating, preventing, or alleviating the symptoms ofdisease, and is not a cover 60 as disclosed herein. Therapeutic agentsinclude non-genetic agents, genetic agents, cellular material, etc.Often the agent will be in the form of a coating or other layer (orlayers) of material placed on a surface region of the prosthesis, whichis adapted to be released at the site of the prosthesis' implantation orareas adjacent thereto. In some embodiments, the controlled ingrowthfeature 40 has a therapeutic agent deposited thereon.

PROSTHESIS EXAMPLES

Exemplifications of a prosthesis 10 as described above are provided bythe following non-limiting examples.

Example 1

FIG. 2 shows an example of a prosthesis 10 with at least protrudingelement 40. Specifically, the prosthesis 10 has a single layer ofscaffolding 18 in the form of a mesh 22 with a protruding scaffoldingfilament section 42; and a cover 60.

The prosthesis has a longitudinal length of 102 mm. The end regions ofthe prosthesis 10 have a greater diameter than the middle region, withthe end regions having a diameter of 30 mm, and the middle region havinga diameter of 23 mm.

The scaffolding 18 is formed from 24 scaffolding filaments 20 eachhaving a diameter of 0.009 mm, and comprises Nitinol. The scaffoldingfilaments 20 are braided at a uniform braiding angle.

The cover 60 is non-porous.

In this example, each scaffolding filament 20 with a right handorientation has a protruding scaffolding filament section 42 extendingbetween two scaffolding filament crossings 26 immediately adjacent oneanother, and each protruding scaffolding filament section 42 has aclosed gap 56 and a rounded shape with no sharp bends. Further, theprotruding scaffolding filament sections 42 are substantially alignedabout the circumference of the prosthesis 10. As can be seen a righthand orientation is non-parallel to the longitudinal axis of theprosthesis.

Example 2

FIG. 9 shows another example of a prosthesis 10 with at least onecontrolled tissue ingrowth feature 40. Specifically, the prosthesis 10has a single layer of scaffolding 18 in the form of a mesh 22 with twoprotruding mesh regions 44 a, 44 b; and a cover 60.

The prosthesis 10 has a diameter of 23 mm and a longitudinal length of150 mm. The prosthesis 10 may have a uniform diameter except for theprotruding mesh regions 44. However, the ends of the prosthesis, notshown in FIG. 9, may have a greater diameter than the uniform diametersection shown in FIG. 9. The scaffolding 18 is formed from 24scaffolding filaments 20 each having a diameter of 0.008 mm andcomprises Nitinol.

The cover 60 is non-porous and has a thickness of 40 μm.

Each protruding mesh region 44 a, 44 b forms a circumferential ring thatextends around the entire circumference of the prosthesis; has a gapheight h of 1 mm; and a longitudinal distance d of 10 mm. A longitudinaldistance of 40 mm separates the two protruding mesh regions 44 a, 44 band each protruding mesh region 44 a, 44 b is 45 mm from the closestprosthesis end 12, 14.

Example 3

FIG. 10 shows another example of a prosthesis 10 with at least oneprotruding element 40. The prosthesis 10 shown in FIG. 10 is constructedand arranged for implantation in the esophagus.

The prosthesis has a longitudinal length, and prosthesis end regionswith a greater diameter than the prosthesis middle region.

The prosthesis 10 has a single layer of scaffolding 18 consisting ofrings 28 with protruding ring turns 46; and a cover 60.

The prosthesis 10 has rings 28 with protruding ring turns 46. Half ofthe rings 28 have protruding ring turns 46 oriented towards the secondprosthesis end 14, and half of the rings 28 have protruding ring turns46 oriented towards the first prosthesis end 12. Adjacent rings 28 areseparated by a uniform longitudinal distance 34.

The cover 60 is non-porous and comprises silicone.

Example 4

FIG. 11 shows another example of a prosthesis 10 with at least oneprotruding element 40. The prosthesis 10 shown in FIG. 11 is constructedand arranged for implantation in the stomach.

The prosthesis 10 has a single layer of scaffolding 18 formed of rings28 where at least some of the rings 28 have protruding ring turns 46;and a cover 60.

The prosthesis 10 has a longitudinal length and a variable diameter witha minimum diameter of 15 mm, and a maximum diameter of 40 mm. Adjacentrings 28 are separated by a variable longitudinal distance (e.g.distances 34 a, 34 b). The rings 28 include rings 28 a with a protrudingring turn 46, and rings 28 b with no protruding ring turns 46. The rings28 a with protruding ring turns 46 are arranged in two groups. Withineach group the protruding ring turns 46 of an individual ring 28 a areoriented towards one prosthesis end and the adjacent ring 28 a isoriented toward to other prosthesis end 12, 14. In other words, within agroup of rings 28 a, the orientation of the protruding ring turns 46alternates.

Each ring 28 is formed by a scaffolding filament 20 comprising Nitinol.

The cover 60 is non-porous.

Example 5

FIGS. 15A-C show examples of a prosthesis with a dimple 40.Specifically, the prosthesis 10 has a single layer of scaffolding 18 inthe form of a mesh 22, and a cover defining at least one dimple 40.

The prosthesis has a longitudinal length of 100 mm and a diameter of 24mm.

The cover 60 has a thickness of 0.05-0.15 mm and forms the prosthesisouter surface 16. The cover 60 has a plurality of dimple sections 64each forming a dimple 40; and a non-dimple section 66.

Each dimple 40 is positioned at least 15 mm from the closest prosthesisend 12, 14; has a maximum longitudinal extent of 12.7 mm; a maximumcircumferential extent of 6 mm; and define a gap of 2 mm. The dimples 40are aligned circumferentially and longitudinally.

For the prosthesis 10 shown in FIG. 15A, longitudinally adjacent dimples40 are positioned 44.6 mm apart.

Methods of Manufacture

In general, forming a prosthesis as described above includes: formingthe scaffolding; forming a controlled ingrowth feature; and applying acover to the scaffolding. Forming the controlled ingrowth feature may bea part of forming the scaffolding; a part of forming the cover; or aseparate step. Thus, when the prosthesis is formed, the prosthesis has ascaffolding; a cover; and a controlled ingrowth feature. Manufacturingor formation of the prosthesis is completed before the prosthesis isengaged to a delivery device.

Method 1

An exemplary method of forming a prosthesis 10 with a protruding element40 formed by a separate filament 48 includes one or more of thefollowing: forming the scaffolding 18 by interweaving a scaffoldingfilament 20 into a mesh; securing a separate filament 48 to thescaffolding 18; forming a protruding element 40 from the separatefilament 48, the protruding element 40 being a section 50 of theseparate filament 48; applying a cover 60 to the scaffolding 18; whereinsecuring the separate filament 48 to the scaffolding 18 furthercomprises securing each end region 52, 54 of the separate filament 48 tothe scaffolding 18; wherein the end regions 52,54 may be secured byinterweaving into the scaffolding 18; by bonding to the scaffolding 18;by welding to the scaffolding 18; by wrapping the end regions 52,54around a scaffolding filament 20; and combinations thereof; wherein thescaffolding 18 is formed before the separate filament 48 is secured tothe scaffolding 18; wherein the scaffolding filament 20 is interwoven ona mandrel; wherein the mandrel has a constant diameter; wherein themandrel has end mandrel regions with a greater diameter than a middlemandrel region; and combinations thereof.

Method 2

An exemplary method of forming a prosthesis 10 with a protruding element40 formed by a scaffolding filament 20 includes one or more of thefollowing: forming the scaffolding 18 by interweaving a scaffoldingfilament 20 into a mesh; forming a protruding element 40 from a section42 of the scaffolding filament 20; applying a cover 60 to thescaffolding 18; wherein the scaffolding filament is interwoven on amandrel; wherein the mandrel has a constant diameter; wherein themandrel has end mandrel regions with a greater diameter than a middlemandrel region; and combinations thereof.

A prosthesis formed by this method can have only protruding elements 40with open gaps; only protruding elements with closed gaps; or acombination of protruding elements 40 with open gaps and protrudingelements 40 with closed gaps.

Method 3

An exemplary method of forming a prosthesis 10 with a protruding meshregion 44 includes one or more of the following: forming the scaffolding18 by interweaving a scaffolding filament 20 into a mesh; forming aprotruding mesh region 44; and applying a cover 60 to the scaffolding18, wherein the protruding element 40 is positioned above the cover 60;removing the covered prosthesis from the mandrel; interweaving thescaffolding filament 20 on a mandrel; wherein the mandrel has a constantdiameter; wherein the mandrel has end mandrel regions with a greaterdiameter than a middle mandrel region; and combinations thereof.

Method 4

In one aspect, a method of forming a ring 28 with protruding ring turns46 includes one or more of the following: forming a ring with aplurality of interconnected ring turns 30; wherein forming the ring withthe plurality of interconnected ring turns 30 comprises winding a single(1) scaffolding filament 20 around a mandrel and securing the ends ofthe scaffolding filament 20; wherein securing the ends of thescaffolding filament 20 comprises welding, joining by clips, applyingadhesive, and combinations thereof; wherein the mandrel 84 includes atapered section with a first mandrel diameter md1 and a second mandreldiameter md2 greater than the first diameter, and a slope from the firstmandrel diameter to the second mandrel diameter (see e.g. FIG. 14);wherein the slope from the first mandrel diameter to the second mandreldiameter provides for the uniform angle β of the ring 28 from the firstdiameter 27 a to the second diameter 27 b; wherein the mandrel furtherincludes a cylindrical section with a second uniform mandrel diameter;wherein the slope of the tapered section of the mandrel from thecylindrical section to the second mandrel diameter provides for theuniform angle β of the ring from the cylindrical section of the ring tothe second diameter of the ring; wherein the ring turns 30 formed at thesecond mandrel diameter will be protruding ring turns 46 whenincorporated into a prosthesis 10; wherein the mandrel includesprotrusions extending outwardly from the outer surface of the mandrel84; wherein the single scaffolding filament 20 further forms a pluralityof sections 32, each section 32 extending between two ring turns 30;wherein forming the ring with the plurality of interconnected ring turns30 comprises injection molding a filament material into a mold with adesired shape for the ring; wherein the filament material is polymeric;wherein the prosthesis 10 has a single layer of scaffolding 18; andcombinations thereof.

Method 5

An exemplary method of forming a prosthesis 10 includes one or more ofthe following: mounting the rings 28 onto a mandrel, each ring 28comprising a plurality of interconnected ring turns 30, at least one ofthe rings 28 has a first end with a smaller diameter than a second end;applying a cover 60, the cover 60 interconnecting the rings 28; whereinthe mandrel has a constant diameter; removing the prosthesis 10 from themandrel; wherein the mandrel has end regions with a greater diameterthan a mandrel middle region; wherein all of the rings have a first endwith a smaller diameter than a second end; wherein dip-coating is usedfor applying the cover; wherein spray-coating is used for applying thecover; wherein the cover comprises silicone; and combinations thereof.

Method 6

An exemplary method of forming a cover 60 with a dimple cover section 64comprises one or more of the following: forming a cover template 94 witha dimple; mounting a film in dimple forming device 90; forming a dimple40 in the film; wherein the dimple forming device comprises a plate 92with a surface defining an indentation; wherein the pattern of theindentation corresponds to a predetermined pattern for the cover 60;wherein forming a dimple in the film comprises pressing the film intothe indentation; wherein the film comprises polytetrafluoroethylene; andcombinations thereof.

An exemplary cover template 94 with template dimples 96 is shown in FIG.23. An exemplary device for forming a cover template 94 is the device 90shown in FIG. 23. Although the device 90 shown in FIG. 23 has two plates92, a single plate 92 may be used. One plate 92 has at least one platedimple or indentation in the surface of the plate.

Method 7

An exemplary method of forming a prosthesis 10 with at least one dimple40 comprises one or more of the following: mounting the scaffolding 18on a mandrel 84 with a recess 86; applying coating material to themounted scaffolding; wherein the scaffolding is positioned a distanceabove the recess 86; wherein the scaffolding 18 conforms to the recess86; wherein dip-coating is used for applying the material of the cover60; wherein spray-coating is used for applying the material of the cover60; wherein the material of the cover 60 comprises silicone; andcombinations thereof.

A schematic example of a mandrel 84 with a recess 86 is provided in FIG.22.

Method 8

An exemplary method of forming a prosthesis 10 with a dimple 40comprises one or more of the following: securing a cover 60 with adimple 40 to an expandable prosthesis 10, the expandable prosthesisdefining a plurality of scaffolding openings 24; wherein the cover 60forms a prosthesis outer surface 16; wherein the cover 60 is secured tothe prosthesis by an adhesive; wherein the cover 60 is secured to theprosthesis by a suture; wherein the scaffolding 18 has a uniformdiameter; and combinations thereof.

Method 9

An exemplary method of forming a prosthesis 10 with a reinforced dimple40 comprises one or more of the following: forming a scaffolding 18comprising a first region with a first diameter and a second region witha second diameter greater than the first diameter; applying a covermaterial to the scaffolding; wherein the coated first region is areinforced dimple; wherein the first region extends around thecircumference of the prosthesis.

Method 10

An exemplary method of forming a prosthesis 10 with a dimple patch 68comprises one or more of the following: forming an opening in a sidewall of an expandable prosthesis 10; and attaching a dimple patch 68 tothe expandable prosthesis so that the dimple patch covers the openingformed in the side wall, wherein the dimple patch is sized to extendinward into the opening of the side wall when the prosthesis isimplanted; wherein forming the opening in the side wall is part offorming the scaffolding of the expandable prosthesis;

wherein forming the opening in the side wall comprises removing a partof a scaffolding of the prosthesis; wherein the expandable prosthesis isselected from the group consisting of stents; covered stents; andstent-grafts; wherein the dimple patch is reinforced with a secondaryscaffolding, the secondary scaffolding positioned between an innersurface and an outer surface of the dimple patch; wherein the dimplepatch comprises silicone; and combinations thereof.

Materials Cover/Dimple Patch

Suitable materials for the cover 60 and the dimple patch include anyother type of material that prevents tissue ingrowth therethrough. Inone aspect, the cover 60 is non-porous. Non-limiting examples includesilicone elastomers, polyurethane,polystyrene-polyisobutylene-polystyrene triblock copolymer (SIBS),polytetrafluroethylene (PTFE), expanded polytetrafluroethylene (ePTFE),and combinations thereof.

Scaffolding/Separate Filament/Scaffolding Patch

The scaffolding 18, the separate filament 48, and scaffolding patch maybe balloon expandable or self-expandable, and may be made from anysuitable biocompatible materials including one or more polymers, one ormore metals or combinations of polymer(s) and metal(s). Examples ofsuitable metals include, but are not limited to, stainless steel,titanium, tantalum, platinum, tungsten, gold and alloys of any of theabove-mentioned metals. Examples of suitable alloys includeplatinum-iridium alloys; cobalt-chromium alloys including Elgiloy andPhynox; nickel-cobalt-chromium-molybdenum alloy such as MP35N; andnickel-titanium alloys, for example, Nitinol; and doped ternary alloyssuch as NiTiCo and NiTiCr.

The scaffolding 18 may be made of shape memory materials (metallic suchas Nitinol; or polymeric, e.g. polyethylene terephthalate (PET)); or maybe made of materials which are plastically deformable. Shape memorymaterials may be processed to have a shape memory effect orsuperelasticity. In the case of shape memory materials with a shapememory effect, the prosthesis may be processed to have a memorizedshape, and then deformed to a reduced diameter shape for delivery to abody lumen. The prosthesis may restore itself to its memorized shape ina body lumen upon being heated to a transition temperature and havingany restraints removed therefrom.

The scaffolding 18 may be made of biodegradable or bioabsorbablematerials will undergo breakdown or decomposition into harmlesscompounds as part of a normal biological process. Suitable biodegradableor bioabsorbable materials include polylactic acid, polyglycolic acid(PGA), collagen or other connective proteins or natural materials,polycaprolactone, hylauric acid, adhesive proteins, co-polymers of thesematerials as well as composites and combinations thereof andcombinations of other biodegradable polymers. Other polymers that may beused include polyester and polycarbonate copolymers.

Therapeutic Agents

Some examples of suitable non-genetic therapeutic agents include but arenot limited to: anti-thrombogenic agents such as heparin, heparinderivatives, vascular cell growth promoters, growth factor inhibitors,Paclitaxel, etc. Where an agent includes a genetic therapeutic agent,such a genetic agent may include but is not limited to: DNA, RNA andtheir respective derivatives and/or components; hedgehog proteins, etc.Where a therapeutic agent includes cellular material, the cellularmaterial may include but is not limited to: cells of human origin and/ornon-human origin as well as their respective components and/orderivatives thereof. Where the therapeutic agent is delivered by apolymer agent, the polymer agent may be apolystyrene-polyisobutylene-polystyrene triblock copolymer (SIBS),polyethylene oxide, silicone rubber and/or any other suitable substrate.

The above disclosure is intended to be illustrative and not exhaustive.This description will suggest many variations and alternatives to one ofordinary skill in this art. The various elements shown in the individualfigures and described above may be combined or modified for combinationas desired. All these alternatives and variations are intended to beincluded within the scope of the claims where the term “comprising”means “including, but not limited to”.

Further, the particular features presented in the dependent claims canbe combined with each other in other manners within the scope of thedisclosure such that the disclosure should be recognized as alsospecifically directed to other embodiments having any other possiblecombination of the features of the dependent claims. For instance, forpurposes of claim publication, any dependent claim which follows shouldbe taken as alternatively written in a multiple dependent form from allprior claims which possess all antecedents referenced in such dependentclaim if such multiple dependent format is an accepted format within thejurisdiction (e.g. each claim depending directly from claim 1 should bealternatively taken as depending from all previous claims). Injurisdictions where multiple dependent claim formats are restricted, thefollowing dependent claims should each be also taken as alternativelywritten in each singly dependent claim format which creates a dependencyfrom a prior antecedent-possessing claim other than the specific claimlisted in such dependent claim below.

This completes the description of the disclosure. Those skilled in theart may recognize other equivalents to the specific embodiment describedherein which equivalents are intended to be encompassed by the claimsattached hereto.

What is claimed is:
 1. A prosthesis for controlled tissue ingrowth whenimplanted in a body lumen comprises: a scaffolding extending from afirst prosthesis end to a second prosthesis end, the scaffoldingcomprising; a cover; a controlled ingrowth feature constructed andarranged to abut an inner surface of a lumen wall when the prosthesis isimplanted in the body lumen, the controlled ingrowth feature selectedfrom the group consisting of protruding elements and dimples; whereinthe controlled ingrowth feature is formed by a scaffolding filament; bya separate filament; by the cover; and combinations thereof.
 2. Theprosthesis of claim 1, wherein the controlled ingrowth feature forms amaximum of about 30% of an outer surface area of the prosthesis.
 3. Theprosthesis claim 1, wherein the controlled ingrowth feature is aprotruding element, the protruding element selected from the groupconsisting of a protruding scaffolding filament section; a separatefilament attached to the scaffolding; a protruding mesh region; and aprotruding ring turn.
 4. The prosthesis of claim 3, wherein theprosthesis has a single layer of scaffolding, the scaffolding is a meshcomprising a scaffolding filament, the protruding element is aprotruding scaffolding filament section, wherein the protrudingscaffolding filament section: is oriented at a non-parallel angle to alongitudinal axis of the prosthesis; has a first end and a second endseparated by a distance of about 1.5 mm to about 7.5 mm; and defines agap with a maximum gap height of about 0.25 mm to about 2 mm, whereinthe gap is selected from the group consisting of an open gap and aclosed gap.
 5. The prosthesis of claim 3, wherein the prosthesis has asingle layer of scaffolding, the scaffolding is a mesh comprising ascaffolding filament, the protruding element is a protruding meshregion, wherein the protruding mesh region: defines an open gap with amaximum gap height of about 0.25 mm to about 2 mm; and has a first edgeand a second edge separated by a longitudinal distance of about 2 mm toabout 10 mm.
 6. The prosthesis of claim 3, wherein the prosthesis has asingle layer of scaffolding, the scaffolding comprises a ring withprotruding ring turns, the protruding element being the protruding ringturns, wherein the protruding ring turns extend outwardly at a singleuniform slope and define a maximum gap height of about 0.25 to about 2mm.
 7. The prosthesis of claim 1, wherein the controlled ingrowthfeature is a dimple, wherein the dimple is selected from the groupconsisting of a dimple cover section of the cover; a reinforced dimplecomprising a dimple cover section and a section of the scaffolding; anda dimple patch; and combinations thereof
 8. The prosthesis of claim 7,wherein the dimple: defines a dimple gap with a maximum gap height ofabout 3 mm; has a maximum longitudinal extent of about1 mm to about 10mm, the maximum longitudinal extent less than a longitudinal length ofthe prosthesis; has a maximum circumferential extent of about 1 mm toabout 10 mm.
 9. The prosthesis of claim 8, wherein the dimple gap spansa single scaffolding opening or a plurality of scaffolding openings. 10.The prosthesis of claim 8, wherein the dimple is the dimple coversection of the cover.
 11. The prosthesis of claim 8, wherein scaffoldingextends over the dimple gap, wherein the scaffolding extending over thedimple gap is either a portion of the scaffolding or a scaffolding patchattached to the prosthesis outer surface.
 12. The prosthesis of claim 8,wherein the scaffolding is a mesh, wherein the dimple is the dimplepatch.
 13. A prosthesis constructed and arranged for controlled tissueingrowth when implanted, the prosthesis comprising: a scaffolding; acover extending over an outer surface of the scaffolding; and acontrolled ingrowth feature forming a maximum of about 30% of an outersurface area of the prosthesis;
 14. The prosthesis of claim 13, whereinthe controlled ingrowth feature is a protruding element constructed andarranged to have limited flex.
 15. The prosthesis of claim 14, whereinthe protruding element forms about to 20% of the outer surface area ofthe prosthesis and defines a gap with a maximum gap height of about 0.25to about 2 mm.
 16. The prosthesis of claim 13, wherein the controlledingrowth feature is a dimple, the dimple defining a gap with a maximumgap height of about 3 mm.
 17. A prosthesis comprising: a meshscaffolding, the mesh scaffolding having a scaffolding outer surface; acover engaged to the scaffolding outer surface, the cover comprising anon-dimple cover section and a dimple cover section, the dimple coversection entirely surrounded by the non-dimple cover section.
 18. Theprosthesis of claim 17, the dimple cover section forming a dimple gap,wherein a portion of the mesh scaffolding extends over the dimple gap.19. The prosthesis of claim 17, the dimple cover section forming adimple gap, wherein a scaffolding patch extends over the dimple gap andis secured to the non-dimple cover section.
 20. The prosthesis of claim19, wherein the dimple cover section spans a scaffolding opening havinga larger size than other scaffolding openings.